Australia's rivers are in crisis

When the River Murray runs backwards – as it did recently – and its mouth closes over, as it is threatening to do, it’s a sign that something is gravely wrong.

We don’t just see the problem in closure of the Murray Mouth, but also in declining water quality, the rising levels of salinity, the dying forests and floodplains, the loss of fish, birdlife and other aquatic animals and plants, the silence of the bush. Old Man Murray is telling us something – and it’s high time we started to listen.

The difficulty is that many of the changes that turn a healthy river into a dying river are imperceptible. They take place over such long spans of time that few people notice them, or recall clearly the way things used to be.

Scientific study of Australia’s rivers and estuaries suggests they can absorb a lot of punishment, degrading slowly until quite suddenly, they reach a point of no-return and the system dies or changes completely for the worse. The challenge is how to awake ourselves to it, in time to prevent a collapse.

We have seen it in the Gippsland lakes, where more and more water was extracted for Melbourne, for the LaTrobe valley and for farming. The loss of flushing with fresh water led, imperceptibly, to the collapse of a healthy brackish water system filled with fish and seagrasses.

It became a turbid, nutrient-polluted, saline system dominated by algae. The salt wedge pushing up from the sea against the weakened flow has largely destroyed the natural system. Nutrients from erosion, sewage and from farming, no longer flushed to sea, have nourished the algae.

It is extremely difficult, if not impossible, to reverse such a process. The only real option is to restore some of the Lakes’ natural flow regime, to put back part of the fresh water. And that requires a complicated discussion and decisions about all the other things we use and value the water for – drinking, power, irrigation, manufacturing. It’s a question of values.

As Australians, we love our rivers, our estuaries, lakes and coastlines. None of us wants to lose them or ruin them.

The irony is that’s exactly what we are doing. In some cases we’re simply unaware of the process, because its signs so hard to read until the crisis breaks.

The threat to our landscape is by no means confined to its waterways. Many people who visit the bush say they come back refreshed because of its silence and peacefulness.

There are two kinds of silence however: natural quiet, and the silence of the tomb. If you visit parts of Australia where the bush is still intact, you will find it is far from silent. Birds, insects and small scurrying marsupials make a constant chorus of sound, which can be quite deafening. That is the bush our forebears went into and enjoyed.

The silence of the bush is like an algal bloom in a great river. They are both signs that the complex web of life that used to prevail has broken, and only fragments of it remain. Where once there were hundreds of species, only a few hang on in the simplified ecosystem. The rest are gone, moved away, locally extinct and sometimes, totally extinct.